CHACHA20 ENCRYPTION TOOL
Other Crypto Algorithms
AES-128-CBC AES-128-CBC-CTS AES-128-CBC-HMAC-SHA1 AES-128-CBC-HMAC-SHA256 AES-128-CCM AES-128-CFB AES-128-CFB1 AES-128-CFB8 AES-128-CTR AES-128-ECB AES-128-GCM AES-128-GCM-SIV AES-128-OCB AES-128-OFB AES-128-SIV AES-128-WRAP AES-128-WRAP-INV AES-128-WRAP-PAD AES-128-WRAP-PAD-INV AES-128-XTS AES-192-CBC AES-192-CBC-CTS AES-192-CCM AES-192-CFB AES-192-CFB1 AES-192-CFB8 AES-192-CTR AES-192-ECB AES-192-GCM AES-192-GCM-SIV AES-192-OCB AES-192-OFB AES-192-SIV AES-192-WRAP AES-192-WRAP-INV AES-192-WRAP-PAD AES-192-WRAP-PAD-INV AES-256-CBC AES-256-CBC-CTS AES-256-CBC-HMAC-SHA1 AES-256-CBC-HMAC-SHA256 AES-256-CCM AES-256-CFB AES-256-CFB1 AES-256-CFB8 AES-256-CTR AES-256-ECB AES-256-GCM AES-256-GCM-SIV AES-256-OCB AES-256-OFB AES-256-SIV AES-256-WRAP AES-256-WRAP-INV AES-256-WRAP-PAD AES-256-WRAP-PAD-INV AES-256-XTS ARIA-128-CBC ARIA-128-CCM ARIA-128-CFB ARIA-128-CFB1 ARIA-128-CFB8 ARIA-128-CTR ARIA-128-ECB ARIA-128-GCM ARIA-128-OFB ARIA-192-CBC ARIA-192-CCM ARIA-192-CFB ARIA-192-CFB1 ARIA-192-CFB8 ARIA-192-CTR ARIA-192-ECB ARIA-192-GCM ARIA-192-OFB ARIA-256-CBC ARIA-256-CCM ARIA-256-CFB ARIA-256-CFB1 ARIA-256-CFB8 ARIA-256-CTR ARIA-256-ECB ARIA-256-GCM ARIA-256-OFB CAMELLIA-128-CBC CAMELLIA-128-CBC-CTS CAMELLIA-128-CFB CAMELLIA-128-CFB1 CAMELLIA-128-CFB8 CAMELLIA-128-CTR CAMELLIA-128-ECB CAMELLIA-128-OFB CAMELLIA-192-CBC CAMELLIA-192-CBC-CTS CAMELLIA-192-CFB CAMELLIA-192-CFB1 CAMELLIA-192-CFB8 CAMELLIA-192-CTR CAMELLIA-192-ECB CAMELLIA-192-OFB CAMELLIA-256-CBC CAMELLIA-256-CBC-CTS CAMELLIA-256-CFB CAMELLIA-256-CFB1 CAMELLIA-256-CFB8 CAMELLIA-256-CTR CAMELLIA-256-ECB CAMELLIA-256-OFB CHACHA20 CHACHA20-POLY1305 DES-EDE-CBC DES-EDE-CFB DES-EDE-ECB DES-EDE-OFB DES-EDE3-CBC DES-EDE3-CFB DES-EDE3-CFB1 DES-EDE3-CFB8 DES-EDE3-ECB DES-EDE3-OFB DES3-WRAPThe ChaCha20 algorithm is a stream cipher designed for high-speed encryption with strong security properties. It is a variant of the original Salsa20 cipher, developed to improve diffusion and resistance to cryptanalysis while maintaining efficiency on modern processors. ChaCha20 operates on 512-bit internal state blocks arranged as a 4x4 matrix of 32-bit words, combining a 256-bit key, a 64-bit nonce, and a 64-bit block counter to generate a pseudorandom keystream.
State Initialization
ChaCha20 begins by initializing its internal state. The first four words contain constant values derived from the ASCII string "expand 32-byte k". The next eight words are the 256-bit encryption key, split into eight 32-bit segments. Two additional words store the block counter, which increments for each 64-byte block of output, ensuring unique keystream blocks. The final two words contain the 64-bit nonce, providing randomness for each encryption session.
Quarter Round Function
The core operation of ChaCha20 is the quarter round function, applied repeatedly to subsets of the state matrix. Each quarter round consists of modular addition, XOR, and bitwise rotation operations on four 32-bit words. This sequence ensures rapid diffusion of input bits across the state matrix, spreading the influence of key, counter, and nonce bits uniformly throughout the state. The algorithm performs 20 rounds of these operations, organized as ten column rounds and ten diagonal rounds, enhancing resistance against linear and differential attacks.
Keystream Generation
After completing the 20 rounds, the algorithm adds the original input state to the transformed state word-by-word modulo 2³². The resulting 512-bit block is serialized into 64 bytes of keystream. This keystream is XORed with plaintext data to produce ciphertext or with ciphertext to retrieve plaintext. Because the keystream is generated independently of the input message, ChaCha20 can encrypt or decrypt data in parallel and supports random access to any block in the stream.
Security Properties
ChaCha20 provides strong resistance to known cryptanalytic attacks, including differential, linear, and rotational attacks, due to its high diffusion rate and nonlinearity. Its 256-bit key size and unique nonce per message ensure a large keyspace, preventing key-recovery attacks. Unlike block ciphers, it does not require padding, making it suitable for encrypting arbitrary-length messages efficiently. The simplicity of its operations also minimizes side-channel vulnerabilities such as timing attacks.
Performance Characteristics
The algorithm is optimized for software implementation, especially on modern 32-bit and 64-bit CPUs. It avoids data-dependent branches and memory accesses, enabling consistent execution time and high throughput. ChaCha20 is widely adopted in protocols requiring secure and efficient encryption, including TLS and various VPN solutions, due to its balance of security, speed, and simplicity. Its design allows for fast parallel computation while maintaining robust cryptographic guarantees.